EP0366390B (Takasago International Corporation) relates to ruthenium complexes containing BINAP. Faraone et al (Inorganica Chimica Acta, 34 (1979) L251-L253) relates to neutral binuclear and cationic mononuclear η6-benzeneruthenium(II) complexes containing neutral bidentate ligands. The article describes that cationic complexes of [(η6—C6H6)Ru{Ph2E(CH2)nEPh2}Cl]Cl (E=P, As n=2; E=P, n=3, 4) are produced on reaction of [(η6-C6H6)RuCl2]2 with the bidentate ligands Ph2P(CH2)nPPh2 (n=2, 3, 4) and Ph2As(CH2)nAsPh2, in a molar ratio 1:2, in refluxed ethanol.